[en] Air-Water Loop (AWL) is an experimental facility aimed at the simulation of two-phase flow phenomenon relevant to steam drum of Advanced Heavy Water Reactor (AHWR). AWL consists of scaled down model of AHWR steam drum, operating with air-water mixture. Scaling has been performed such that the superficial velocities of both phases in the model are identical to that in the prototype. The required boundary flow, i.e. two phase air-water flow at drum inlet is generated using two-phase natural circulation loop formed by pipe channels connected between the drum and a water tank. Air is injected at the bottom of channels and is separated in the drum. Steady state experiments have been performed in AWL at various operating levels in drum and air injection flow rates. The experimental data has been validated using a numerical model developed based on momentum balance in channels. This paper describes the geometry of the experimental facility, details of two-phase natural circulation experiments carried out and validation of experimental data. (author)